Surface tension by pendant drop

Hansen, Finn Knut; Rødsrud, G

doi:10.1016/0021-9797(91)90296-k

Cited by 233 publications

(105 citation statements)

References 6 publications

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“…85 In tensiometry, a pendant liquid droplet is formed inside an immiscible fluid, and the surface tension of the droplet is measured over time. 78,86,87 Decreasing surface tension elongates the profile of a pendant droplet from spherical (Figure 2a) to teardrop (Figure 2b) (Figure 3b, open symbols), indicating that BSA did not adsorb to the interface that presented the R f -OEG surfactant. Similarly, we found that fibrinogen adsorbed to interfaces presenting either of the R f -COOH (Figure 4a) or R f -CH 2 CH 2 OH (Figure 4b) surfactants, but not the R f -OEG surfactant (Figure 4c, d).…”

Section: Adsorption Measurements Within Droplets Using Drop Tensiometrymentioning

confidence: 99%

Controlling Nonspecific Protein Adsorption in a Plug-Based Microfluidic System by Controlling Interfacial Chemistry Using Fluorous-Phase Surfactants

2004

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Control of surface chemistry and protein adsorption is important for using microfluidic devices for biochemical analysis and high-throughput screening assays. This paper describes the control of protein adsorption at the liquid-liquid interface in a plug-based microfluidic system. The microfluidic system uses multiphase flows of immiscible fluorous and aqueous fluids to form plugs, which are aqueous droplets that are completely surrounded by fluorocarbon oil and do not come into direct contact with the hydrophobic surface of the microchannel. Protein adsorption at the aqueous-fluorous interface was controlled by using surfactants that were soluble in fluorocarbon oil but insoluble in aqueous solutions. Three perfluorinated alkane surfactants capped with different functional groups were used: a carboxylic acid, an alcohol, and a triethylene glycol group that was synthesized from commercially available materials. Using complementary methods of analysis, adsorption was characterized for several proteins (bovine serum albumin (BSA) and fibrinogen), including enzymes (ribonuclease A (RNase A) and alkaline phosphatase). These complementary methods involved characterizing adsorption in microliter-sized droplets by drop tensiometry and in nanoliter plugs by fluorescence microscopy and kinetic measurements of enzyme catalysis. The oligoethylene glycolcapped surfactant prevented protein adsorption in all cases. Adsorption of proteins to the carboxylic acid-capped surfactant in nanoliter plugs could be described by using the Langmuir model and tensiometry results for microliter drops. The microfluidic system was fabricated using rapid prototyping in poly(dimethylsiloxane) (PDMS). Black PDMS micro-fluidic devices, fabricated by curing a suspension of charcoal in PDMS, were used to measure the changes in fluorescence intensity more sensitively. This system will be useful for microfluidic bioassays, enzymatic kinetics, and protein crystallization, because it does not require surface modification during fabrication to control surface chemistry and protein adsorption. This paper describes the biocompatibility of a plug-based microfluidic system obtained through control of surface chemistry the aqueous-fluorous interface. This microfluidic system uses multiphase flows of immiscible fluorous and aqueous liquids to form droplets (plugs) and to transport them with rapid mixing and no Taylor-like dispersion. 1 We have previously used the system to measure enzyme kinetics 2 and perform protein crystallization 3-6 using submicroliter volumes of sample.

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Section: Adsorption Measurements Within Droplets Using Drop Tensiometrymentioning

confidence: 99%

Controlling Nonspecific Protein Adsorption in a Plug-Based Microfluidic System by Controlling Interfacial Chemistry Using Fluorous-Phase Surfactants

2004

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“…Andreas et al 2) introduced a shape factor, H, based on the shape of the pendant drop, and gave a convenient relationship, (3) where d e is the equatorial diameter of the drop. Hansen et al 6) have developed a numerical calculation method for the drop profile. They calculated theoretical dimensionless profiles for β = 0.100 to 0.500, in steps of 0.001 by means of the Kutta-Merson numerical integration algorithm.…”

Section: Pendant Drop Methodsmentioning

confidence: 99%

“…So far, many experimental methods to obtain the interfacial tension between polymer melts have been proposed. [1][2][3][4][5][6][7][8][9][10][11][12] The pendant drop method [2][3][4][5][6] is well-known as a simple static method of measurement of the interfacial tension between low-molecular weight liquid material and air, and between polymers. When a polymer drop like a pendant is suspended at the end of the capillary tube in another polymer, the drop shape is determined only by two forces; the force reducing the free energy of the interface between the polymers, that is, interfacial tension, and the gravity of the drop.…”

Section: Introductionmentioning

confidence: 99%

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Measurement of Interfacial Tension between Polymer Liquids : Pendant Drop, Improved Imbedded Fiber Retraction and Steady Shear Flow Methods

Hayashi

Takahashi

Yamane

2000

J. Soc. Rheol., Jpn

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The interfacial tension between a poly (isobutylene) (PIB) and a poly (dimethylsiloxane) (PDMS) was obtained by an improved imbedded fiber retraction method from the observation of the PDMS (or PIB) droplet shape in the PIB (or PDMS) matrix after application of the step shear strain. The interfacial tension was also obtained from the observation of the PDMS (or PIB) droplet shape during the steady shear flow. We compared the values of interfacial tension obtained by these methods with the value determined by the pendant drop method. It was found that these values agree fairly well when the viscosity ratio of the droplet to the matrix is around unity.

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“…Surface tension measurements by the pendant-drop shape analysis. The surface tension measurements were performed by the pendant-drop method employing the digital image analysis of the drop shape [11]. This strategy evaluates the error between the physically observed drop shape and a theoretical model of drop outline, i.…”

Section: Chemicalsmentioning

confidence: 99%

The interfacial behavior of cytochrome c studied by pendant‐drop technique

et al. 1998

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SUMMARYThe adsorption properties of cytochrome c (cyt c) were characterized by surface tension measurements using the pendant-drop method employing the digital image analysis of the drop shape. The method was applied to the study of the protein conformation change due to acidification at low ionic strength. The observation of the saturated steady-state surface tension shows that decrease in pH induces its cooperative change centered around pH 2.5. This value is equal to the value of apparent pK of the acid-induced transition of the horse ferricyt c from a native state to the unfolded conformation. This indicates that the saturated steady-state surface tension is sensitive to the conformation ofcyt c in bulk phase, and the pendant-drop method might be used to monitor changes in the tertiary structure of proteins.

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Surface tension by pendant drop

Cited by 233 publications

References 6 publications

Controlling Nonspecific Protein Adsorption in a Plug-Based Microfluidic System by Controlling Interfacial Chemistry Using Fluorous-Phase Surfactants

Controlling Nonspecific Protein Adsorption in a Plug-Based Microfluidic System by Controlling Interfacial Chemistry Using Fluorous-Phase Surfactants

Measurement of Interfacial Tension between Polymer Liquids : Pendant Drop, Improved Imbedded Fiber Retraction and Steady Shear Flow Methods

The interfacial behavior of cytochrome c studied by pendant‐drop technique

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